This test measures how well you see at various distances. It is the familiar eye chart test.
The eye chart itself -- the usual one is called Snellen's chart -- is imprinted with block letters that line-by-line decrease in size, corresponding to the distance at which that line of letters is normally visible.
The letters on Snellen's chart are, not surprisingly, called Snellen's test type. Each block letter is quite scientific in design (so that at the appropriate distance the letter subtends a visual angle of 5 degrees and each component part subtends an angle of 1 minute).
The chart and the letters are named for a 19th-century Dutch ophthalmologist Hermann Snellen (1834-1908) who came up with them as a test of visual acuity. Visual acuity refers to the clarity or clearness of the vision, a measure of how well a person sees. The word "acuity" comes from the Latin "acuitas" = sharpness.
medical
dictionary, online medical dictionary, medical
terminology dictionary, free online medical
dictionary, medical dictionary, online medical
dictionary, medical terminology dictionary, free
online medical dictionary, dictionary medical,
dictionary medical online, dictionary medical
terminology, dictionary free medical online,
dictionary free medical, dictionary medical
terms, dictionary drug medical medicine,
dictionary health illustrated medical nursing
profession stedmans, dictionary English medical,
dictionary medical online terminology,
dictionary encyclopedia medical online,
condition dictionary medical, dictionary
medical, dictionary drug medical, medical
dictionary software, cyclopedic dictionary index
medical tabers thumb, medical dictionary, online
medical dictionary, medical terminology
dictionary
